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PubMed1987

Technetium pyrophosphate labelling following catheter shock: potential for a new intraoperative mapping technique.

Technetium pyrophosphate uptake at the site of catheter shock was studied in four patients and seven experimental dogs. Technetium pyrophosphate scintigraphy was performed following five catheter ablation attempts in humans at different cardiac sites, and following 24 J catheter shocks delivered in the right and left ventricles of seven dogs. In the patients, gamma camera imaging with tomographic reconstruction showed intense focal uptake at the sites of shock. The scans were positive from 1.5 to 5.5 h following ablation and stayed positive for up to five days. In the animals, the low energy shocks produced circumscribed areas of coagulation and contraction band necrosis. The binding of technetium pyrophosphate at these sites was confirmed by in vivo gamma camera imaging, epicardial counting with a 1.2 cm scintillation probe and ex vivo imaging. Ratios of focal binding to normal myocardial uptake of technetium pyrophosphate were calculated from the digital gamma camera images. In all cases, technetium pyrophosphate was bound to myocardial sites where transcatheter energies were delivered in both humans and dogs. Intraoperative localization of the origin of tachycardia in man may be facilitated by combining preoperative endocardial catheter mapping, catheter shock, radionuclide labelling of the site of shock and a search for the focus of radionuclide concentration during subsequent surgery.

Aged↗
PubMed1996

Detecting infection and inflammation with technetium-99m-labeled Stealth liposomes.

UNLABELLED: The performance of 99mTc Stealth liposomes was investigated in various rat models. METHODS: Preformed polyethyleneglycol-containing liposomes with encapsulated reduced glutathione, were radiolabeled using the lipophilic 99mTc-HMPAO. The labeled liposomes were intravenously administered to rats with focal S. aureus or E. coli infection, or turpentine-induced inflammation. For comparison, Tc-99m-nanocolloid- and 99mTc-labeled nonspecific IgG were tested. In rats with Pneumocystis carinii pneumonia (PCP), Tc-99m-liposomes were directly compared to In-111 labeled nonspecific IgG. RESULTS: Technetium-99m-liposomes accumulated in the infectious and inflammatory muscle foci over 24 hr (0.59% injected dose per gram tissue (%ID/g) for S. aureus; 1.18 %ID/g for turpentine). Abscess-to-muscle ratios increased to values as high as 24.0, 41.7 and 44.5 for the respective models at 24 hr postinjection. Technetium-99m-liposomes visualized the foci as early as 1 hr postinjection. Technetium-99m-IgG visualized S. aureus infection, but abscess-to-muscle ratios and abscess uptake at the later time points were significantly lower. Technetium-99m-nanocolloid failed to visualize any of the muscle foci. In PCP however, 99mTc-liposomes did not show preferential localization in the infection. The control agent 111In-IgG showed a significant, two-fold increase in lung uptake. CONCLUSION: Technetium-99m-Stealth liposomes preferentially accumulated in abscesses, leading to very high target-to-nontarget ratios. This property appears to be related to a process based on uptake of long-circulating particles. In a specific type of infection, i.c. PCP, 99mTc-liposomes did not accumulate in diseased lung tissue, thus mimicking the in vivo behavior of labeled leukocytes.

Abscess↗
PubMed1996

Preoperative technetium Tc 99m sestamibi imaging. Paving the way to minimal-access parathyroid surgery.

OBJECTIVE: To examine the reliability of technetium Tc 99m sestamibi scanning as a new adjunct to the surgical management of hyperparathyroidism. DESIGN: Preoperative localization of parathyroid adenoma by technetium Tc 99m sestamibi delayed washing-out scanning and high-resolution ultrasound was compared with a historical institutional experience of surgical intervention without preliminary localization studies. A 10-year retrospective review from 1985 to 1995 of patients with surgical hyperparathyroidism was performed. SETTING: Academic tertiary referral medical center. PATIENTS: Thirty-three technetium Tc 99m sestamibi scans in patients with primary hyperparathyroidism were correlated with eventual surgical and pathologic findings. The last 10 patients were also studied with 10-MHz linear transducer ultrasound, and the results were compared with those of the radionuclide scan and eventual surgical and pathologic findings. From 1985 to 1995, 142 patients underwent surgical exploration for primary hyperparathyroidism, and 125 records were available for review. RESULTS: The technetium Tc 99m sestamibi parathyroid scan correctly identified the site and presence of 31 adenomas among 34 confirmed tumors, a sensitivity of 91% and positive predictive value of 97%. The scan detected three anterior mediastinal adenomas that could not be removed through cervical exploration. In each instance median sternotomy was included in the primary surgery and allowed efficient, successful management of these ectopic adenomas. High-resolution ultrasound correctly identified nine of 10 cervical parathyroid adenomas and predicted the volume of each tumor to a statistically significant level. CONCLUSIONS: Hyperthyroidism has traditionally been treated surgically without preliminary localization studies. We found both technetium Tc 99m sestamibi scanning and high-resolution ultrasound to be highly sensitive at detecting parathyroid adenomas at the 90% level. Furthermore, preoperative localization allowed efficient surgical intervention for our group of patients who had high frequency of mediastinal adenomas that required transmediastinal surgery.

Adenoma↗
PubMed1994

Technetium-99m, rhenium-186, and rhenium-188 direct-labeled antibodies.

BACKGROUND: Antibody sulfhydryl groups can act as effective carriers of reduced technetium and rhenium species for radioimmunodetection and radioimmunotherapy. METHODS: Intact immunoglobulin G and fragments were labeled with the isotopes and examined in vitro and in vivo. RESULTS: Technetium bound to intact immunoglobulin G was found to be the most stable species in vitro, but in vivo, clearances of technetium and rhenium bound to intact antibody were similar. Serum clearances were faster than those seen for the corresponding radioiodinated antibodies. In vivo clearance rates of the radiolabeled fragments were similar, with kidney uptake and retention seen. Rhenium-labeled antibodies, despite a greater tendency toward in vitro reoxidation than technetium-labeled antibodies, did not show enhanced kidney clearance in animal models. Rhenium-188 and technetium-99m were obtained from similar generator systems in carrier-free form. Using rhenium-188 spiked with cold rhenium, it was determined that approximately one rhenium atom per molecule of antibody can be conjugated directly. Rhenium-186 also was coupled at almost a 1:1 ratio to antibody. CONCLUSIONS: Only radiolysis concerns will limit the amount of rhenium-188 conjugated to antibody. Large doses of antibody will be necessary to deliver rhenium-186 at this isotope's currently available specific activity. Otherwise, higher specific activity rhenium-186, and/or greater loading capacity of rhenium-186 onto antibody, will be needed to generate the type of product that will be usable at a clinical dose of several hundred millicuries.

Animals↗
PubMed1993

Myocardial risk area defined by technetium-99m sestamibi imaging during percutaneous transluminal coronary angioplasty: comparison with coronary angiography.

OBJECTIVES: The purpose of this study was to compare the assessment of myocardial area at risk in patients with coronary artery stenosis by coronary angiography and quantitative myocardial perfusion imaging with technetium-99m sestamibi. BACKGROUND: Decisions concerning patient management frequently rely on semiquantitative angiographic estimation of the myocardial area at risk, although this approach has not been well validated. Technetium-99m sestamibi is a perfusion imaging agent with little redistribution after initial myocardial uptake. This characteristic allows for injection during angioplasty and later imaging for visualization and quantitation of the nonperfused area at risk. METHODS: Thirty-nine patients referred for coronary angioplasty were studied. Technetium-99m sestamibi was injected intravenously during angioplasty balloon inflation. Planar (33 patients) or tomographic (6 patients) imaging was performed after completion of angioplasty. Imaging was repeated 24 to 48 h later. Myocardial risk area (perfusion defect on angioplasty image) was quantified as an integral using circumferential count distribution profiles and normal reference. Angiographic risk area was assessed using five scoring methods. RESULTS: The scintigraphic risk area was 14 +/- 15 on planar images and 39 +/- 16 on tomography. Scintigraphic risk area of patients with infarction was larger than in patients without (22 +/- 17 versus 7 +/- 8, p = 0.003). The left anterior descending coronary artery had a larger mean risk area than other vessels (22 +/- 15 versus 7 +/- 11, p = 0.002). The presence of angiographic collateral channels was associated with smaller risk areas. Angiographic risk scores correlated only moderately with the technetium-99m sestamibi risk area (r = 0.54 to 0.65), with considerable spread of data. CONCLUSIONS: Area at risk estimated from coronary angiography does not correlate well with that from quantitative myocardial perfusion imaging with technetium-99m sestamibi. These findings emphasize that the functional significance of coronary artery disease is not predicted by coronary anatomy alone.

Adult↗
PubMed1994

Rest technetium-99m sestamibi tomography in combination with short-term administration of nitrates: feasibility and reliability for prediction of postrevascularization outcome of asynergic territories.

OBJECTIVES: This study investigated the role of nitrate technetium-99m sestamibi imaging in predicting the postrevascularization outcome of chronically hypoperfused asynergic territories. BACKGROUND: Rest technetium-99m sestamibi myocardial scintigraphy underestimates the presence of viable myocardium in asynergic territories. Stimulation that improves coronary blood flow could increase tracer uptake in hibernating territories. METHODS: Nineteen patients with a previous myocardial infarction and left ventricular dysfunction scheduled for revascularization underwent quantitative technetium-99m sestamibi tomography under baseline conditions and during isosorbide dinitrate infusion. Global and regional function were assessed, respectively, before and after revascularization by radionuclide angiocardiography and two-dimensional echocardiography. RESULTS: Seven patients (group A) showed postrevascularization regional function recovery, and 12 (group B) showed no significant changes. In group A, nitrate infusion induced a decrease in the extent of the global uptake defect ([mean +/- SD] -37.4 +/- 21.6% of baseline value); in group B, no change or a slight increase was observed (+5.8 +/- 8.4%, p < 0.0005 vs. group A). The nitrate-induced changes in the extent of uptake defect correlated with postrevascularization changes in ejection fraction (r = -0.94, SEE 7.6). After revascularization, 11 asynergic vascular territories showed improvement (hibernating), and 34 remained unchanged (fibrotic). With administration of nitrates, 10 hibernating territories had a decrease in the extent of uptake defect, whereas only 4 of 34 of the fibrotic territories showed a nitrate-induced uptake improvement. CONCLUSIONS: Short-term administration of isosorbide dinitrate immediately before injection of technetium-99m sestamibi increases tracer uptake in some chronically hypoperfused asynergic territories. This finding correlates with the observation of post-revascularization functional recovery. Nitrate technetium-99m sestamibi myocardial scintigraphy could be a promising method for the noninvasive detection of viable hibernating myocardium.

Coronary Angiography↗
PubMed1986

Technetium-sulfur colloid.

The chemistry of the technetium-sulfur colloid produced by the reaction of sodium thiosulfate with acid was investigated. A commercial kit was duplicated, and analyses of elemental sulfur, bisulfite and residual thiosulfate were carried out. The colloidal dispersions were filtered through Nuclepore graded membranes, and the percentages of sulfur and of 99mTc in the various filtrates were determined. In all cases--with varying acid, thiosulfate and time of incubation--there was a rough agreement between the two percentages for particles 0.4 micron in diameter or more. However, for small particles (less than 0.1 micron) there was virtually no sulfur, but there was an appreciable percentage of technetium. It was concluded that the technetium sulfide nuclei formed first, and that the supersaturated sulfur deposited in part on them and in part on its own nuclei. It was found that raising the pH of the preparation to weakly alkaline values and reheating the solution dissolved most of the deposited sulfur by the reaction with sulfite to form thiosulfate, leaving much smaller, virtually sulfur-free technetium sulfide particles. Such a preparation was found to be as efficient as the technetium-antimony sulfide colloid for lymphograms in dogs. Potassium trithionate, K2S3O6, used in place of sodium thiosulfate, produced small Tc-S colloid particles with less sulfur than the conventional thiosulfate-acid system.

Animals↗
PubMed1989

Factors affecting the sensitivity and specificity of the three-phase technetium bone scan in the diagnosis of reflex sympathetic dystrophy syndrome in the upper extremity.

The three-phase technetium bone scan has been recommended for use in the diagnosis of the reflex sympathetic dystrophy syndrome with a sensitivity and specificity of greater than 90%. A retrospective chart review was conducted of 63 patients who had three-phase technetium bone scan as part of a work-up for unexplained upper extremity pain, to determine the predictive value of the three-phase technetium bone scan in reflex sympathetic dystrophy syndrome, and what factors might affect it. The prevalence of definite or probable reflex sympathetic dystrophy syndrome, as assessed by Kozin's criteria, was 26% in this sample. The 3-hour delayed image demonstrated a sensitivity = 50%; specificity = 92%; positive predictive value = 67%, and negative predictive value = 84%. This was not improved using the data from the blood flow or pool phase. The sensitivity of 50% is lower than previous reports. The predictive value of the three-phase technetium bone scan was affected by the duration of symptoms and the age of the patient. Duration of symptoms less than 6 months, or ages more than 50 years substantially increased the sensitivity and positive predictive value of the three-phase technetium bone scan.

Adult↗
PubMed2001

Transfer across the human gut of environmental technetium in lobsters (Homarus gammarus L.) from the Irish Sea.

Few data are available on the uptake by the human gut of the element technetium. Of current radiological interest in connection with discharges of technetium-99 in liquid discharges from BNFL, Sellafield, is uptake from European lobsters (Homarus gammarus), whose edible parts are known to concentrate technetium. In this study, a group of eight adult volunteers (six males and two females) ate samples of edible flesh from lobsters caught off the west Cumbrian coast and provided 24 h samples of urine and faeces for analysis. Detection of uptake from the gut by difference between intake and faecal measurements proved insensitive, suggesting a low value of the gut transfer factor (f1 value) of up to 0.1 with a maximum (two standard deviations) level of about 0.3. In urine, technetium was detectable at a relatively low level compared with the intakes, consistent with a low absorption across the gut. Values for f1 were derived with the aid of literature data for excretion following intravenous administration of technetium-95 m as pertechnetate, and gave averaged data for f1 in the range 0.046 to 0.23. These results are in broad conformity with those derived from the faecal measurements, and suggest a lower value than the 0.5 used by ICRP.

Adult↗
PubMed1983

Technetium and uranium: sorption by and plant uptake from peat and sand.

The objectives of this study were to compare the effects of technetium and uranium on the yield and uptake, and to identify the organ of accumulation, of an edible leafy vegetable growing in sandy and peaty soils. In sand, where the soil's sorption capacity is negligible, technetium uptake is four orders of magnitude higher than from peat, suggesting no plant mediation of uptake and thus a constant concentration factor (greater than 50) in an oxidizing environment where technetium is continuously supplied. The technetium is predominantly translocated to the shoots. When soil fixation occurs, as in peat, this becomes the controlling factor in the plant uptake of technetium. In the case of uranium, plant mediation is more significant. Uranium uptake by Swiss chard is up to 80 times higher from sand than from peat. The uranium is restricted to the root system and may only be precipitated on the outer root membrane and may not accumulate in the roots.

Plants, Edible↗
PubMed1987

Accumulation of technetium-99m sulfur colloid by hepatocellular adenoma: scintigraphic-pathologic correlation.

It is currently believed that hepatocellular adenoma is photon deficient on technetium-99m sulfur colloid scintigraphy because these tumors lack Kupffer cells. In a retrospective review of 13 pathologically proven cases of hepatocellular adenoma with technetium-99m sulfur colloid scintigrams, Kupffer cells were present in all 13 cases. We observed uptake of the radiocolloid by the hepatocellular adenoma in three cases (23%), and there were no histologic differences between the tumors with uptake and the ones without it. We conclude that the currently accepted reason for the lack of technetium-99m sulfur colloid uptake within hepatocellular adenoma is incorrect, and an explanation other than a lack of Kupffer cells is responsible for the photon-deficient appearance in the majority of cases of hepatocellular adenoma. Further, because hepatocellular adenoma may have technetium-99m sulfur colloid uptake in a significant percentage of cases, it should be added to focal nodular hyperplasia in the differential diagnosis of a hepatic mass with uptake by technetium-99m sulfur colloid.

Adolescent↗
PubMed2002

Use of plasma clearance of technetium Tc 99m pentetate to estimate renal clearance during postnatal development in pigs.

OBJECTIVE: To compare renal clearance of technetium Tc 99m pentetate with plasma clearance by use of a glomerular filtration rate technique in pigs from 3 to 24 weeks of age. ANIMALS: 24 female pigs. PROCEDURE: At the time of investigation, 5 pigs were 3 weeks old, 6 pigs were 6 weeks old, 8 pigs were 12 weeks old, and 5 pigs were 24 weeks old. Plasma clearance of technetium Tc 99m pentetate was measured by the use of a single injection technique followed by collection of multiple blood samples until 5 hours after the injection. Simultaneously, urine was collected through a urinary catheter, and the renal clearance of technetiumTc 99m pentetate was calculated. Plasma clearance of technetium Tc 99m pentetate was correlated with the renal clearance (r = 0.95). Plasma clearance was higher than renal clearance at all ages (mean, 5.8%), indicating extrarenal clearance of technetium Tc 99m pentetate or methodologic errors. Volume of distribution increased with increasing age but decreased as a fraction of body weight. CONCLUSIONS: Plasma clearance of technetium Tc 99m pentetate estimates renal clearance with acceptable precision when using single injection technique and multiple biood samples in pigs from 3 to 24 weeks of age.

Animals↗
PubMed1999

[Relation between wall motion and scintigraphic uptake altered by the cut-off level on technetium-99m sestamibi tomographic imaging--the preferable cut-off levels according to tomographic uptake correlated with the wall motion].

BACKGROUND: Whether technetium-99m sestamibi imaging can evaluate myocardial viability is still obscure. It may be partially because the preferable cut-off level for evaluation of the viability is not known. OBJECTIVES: This study was aimed to investigate which cut-off level should be used for estimation of the contractile function, and verify whether technetium-99m sestamibi tomographic imaging can evaluate myocardial viability. METHODS: We studied 45 patients who had had myocardial infarction. They underwent technetium-99m sestamibi imaging, echocardiography, and cardiac catheterization. The myocardial image was divided into 16 segments, each of which was scored according to wall motion on echocardiography with a 4-point scale. The segmental technetium-99m uptake was also scored with a 4-point scale. We investigated the correlation between wall motion and scintigraphic uptake with the use of 7 cut-off levels (from 35% to 65%, in 5% increments). The correlation ranks were compared among patient groups with a number of stenotic vessels. RESULTS: Irrespective of the number of stenotic vessels, the defect score was similarly enlarged according to cut-off levels. The patient groups had the maximum correlation ranks with different cut-off levels, which were 40% for 1-vessel disease (rho = 0.512, n = 160, p = 0.0001), 50% for 2-vessel disease (rho = 0.424, n = 208, p = 0.0001), and 60% for 3-vessel disease (rho = 0.540, n = 272, p = 0.0001). The correlation ranks for all groups were stable, whereas not high, throughout various cut-off levels. CONCLUSIONS: Technetium-99m sestamibi imaging can approximately estimate myocardial viability from the point of view of function, which may be corrected by the careful choice of cut off levels according to the number of the stenotic vessels (40% for 1-vessel disease, 50% for 2-vessel disease, 60% for 3-vessel disease).

Coronary Circulation↗
PubMed1991

The pharmacokinetics and biodistribution of technetium-99m(V)dimercaptosuccinic acid in an animal tumor model.

This study used an established rabbit tumor model with squamous carcinoma to evaluate the pharmacokinetics and biodistribution of technetium-99m-(V)dimercaptosuccinic acid. A total of 54 rabbits were studied (25 with no tumor; 29 with tumor). Technetium-99m(V)dimercaptosuccinic acid had a bi-exponential blood clearance in rabbits with no tumors (28 and 325 min) and in rabbits with tumors (27 and 352 min). There was no significant difference (p greater than 0.05) in mean clearance times between the two groups and clearance appeared unaffected by tumor mass. Technetium-99m(V)dimercaptosuccinic acid had a bi-exponential cumulative urine excretion with no apparent difference in half-times between non-tumor and tumor rabbit groups (200 and 240 min, respectively). Technetium-99m(V)dimercaptosuccinic acid had a major organ biodistribution in rabbits which included bone, kidneys, bladder and the blood pool. The major route of excretion was via the urine. There was no significant difference (p greater than 0.05) in organ biodistribution between rabbits with no tumors and rabbits with tumors and there was no evidence of active uptake of technetium-99m(V)dimercaptosuccinic acid by either squamous carcinoma or inflammatory tissue.

Animals↗
PubMed1980

Preparation and biological distribution of technetium diphosphonate radiotracers synthesized without stannous ion.

Two HEDP complexes of technetium (either Tc-99 or a mixture of Tc-99 and Tc-99m) have been prepared without the use of stannous ion. The first, Tc(NaBH4)-HEDP, is synthesized by reduction of TcO4- with NaBH4 in the presence of excess HEDP; this is analogous to the preparation of Tc(Sn)-HEDP in commercial kits wherein SN(II) functions as the reductant. The second, Tc-HEDP, is prepared by substitution of HEDP onto the pre-formed, pre-reduced, technetium center TcBr62-. The HEDP-to-Tc ratio in Tc-HEDP was found to be 1.0 by double-labeling procedures (Tc-99 and [3H]HEDP), implying that in solution this material is polymeric or at least dimeric. Preparations of Tc(NaBH4)-HEDP and Tc-HEDP with Tc-99m are excellent bone-imaging agents in both rats and dogs. Tissue distribution studies in rats show that uptake of Tc(NaBH4)-HEDP and Tc-HEDP by the bone is at least equivalent to that achieved by Tc(Sn)-HEDP prepared in commercial kits with Sn(II) as the reductant. Tin is therefore not necessary for the bone-seeking properties of Tc(Sn)-HEDP, and the in vivo distribution of a given HEDP radiotracer seems to depend primarily on the presence of the HEDP ligand and not on the exact nature of the technetium complex itself. Synthesis of technetium radiotracers by a substitution route, rather than by redox, is practicable; this route has the potential of introducing hitherto unattainable flexibility and subtlety into the preparation of technetium radiotracers.

Etidronic Acid↗
PubMedDate not supplied

Myocardial perfusion scintigraphy in heart transplant recipients with and without allograft atherosclerosis: a comparison of thallium-201 and technetium 99m sestamibi.

Our objectives were to assess the comparative value of thallium-201 and technetium 99m sestamibi for the detection of cardiac allograft atherosclerosis and the left ventricular ejection fraction response to exercise in heart transplant recipients with and without allograft atherosclerosis. Allograft atherosclerosis is the critical factor limiting long-term survival in heart transplant recipients. Annual coronary angiography is invasive and expensive. A noninvasive test to detect allograft atherosclerosis would be clinically useful. Treadmill exercise testing followed by myocardial perfusion single-photon computed tomographic imaging was performed in 25 heart transplant recipients. All patients underwent coronary angiography. Group 1 (13 patients) had angiographic coronary artery disease; group 2 (12 patients) did not. Eighteen patients underwent two exercise tests to equivalent work loads with thallium-201 and technetium 99m sestamibi; seven patients underwent only thallium-201 imaging. First-pass left ventricular ejection fraction was measured during injection of technetium 99m sestamibi. In group 1, 10 of 13 patients had abnormal thallium-201 scans. There was no significant difference in the number of patients who had abnormal thallium-201 (7/10) and technetium 99m sestamibi scans (6/10). Fifty-two percent (12/23) of discordantly scored segments were reversible on thallium-201 and fixed on technetium 99m sestamibi imaging compared with the opposite (0%; 0/23) (p < 0.01). All patients in group 2 had normal perfusion scans. There were no false-positive scans.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1996

Technetium-99m-sestamibi uptake by human benign and malignant breast tumor cells: correlation with mdr gene expression.

UNLABELLED: Early diagnosis of multidrug-resistance (MDR) development is extremely important for the judicious choice of treatment protocols in breast cancer chemotherapy. In this study, the mechanism of 99mTc-sestamibi uptake by nine human breast tumor cell lines was analyzed as a function of P-glycoprotein (PgP) expression. METHODS: Technetium-99m-sestamibi radioactivity incorporation into the cells was determined after different times of incubation at 37 degrees C. We analyzed the mechanism of 99mTc-sestamibi uptake as follows: (a) effect of temperature (4 degrees C); (b) influence of extracellular 99mTc-sestamibi concentration; and (c) competitive inhibition of cell uptake with cold 99mTc-sestamibi. Technetium-99m-sestamibi uptake was compared to the level of PgP determined by Western blotting. The PgP reversing effect of verapamil was evaluated at different drug concentrations (50, 200, 500 microM). RESULTS: Technetium-99m-sestamibi uptake plateaued at 60 min, which was 14 times lower at 4 degrees C than at 37 degrees C and was directly proportional to the extracellular concentration between 0.3 and 10 nM. Technetium-99m-sestamibi percentage uptake by cells expressing nonimmunodetectable levels of PgP was significantly higher (7.3% +/- 0.6% (s.d.) to 14.9% +/- 1.9%) than that by cells expressing high PgP levels (0.7% +/- 0.4%, p < 0.001). In the presence of verapamil, a known reverser of PgP functions, 99mTc-sestamibi uptake was increased by a factor of 2 in cells expressing no detectable levels of PgP and by a factor of 12 in cells with high PgP levels. CONCLUSION: Technetium-99m-sestamibi uptake by these breast tumor cells is energy-dependent but not specific. These data suggest that 99mTc-sestamibi imaging may be used as a noninvasive technique to diagnose the presence of MDR in breast tumors in vivo.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

[Study on technetium-99m in radiopharmaceuticals].

The technetium field involving a new element of which chemistry has not been honed in the research during the century is particularly challenging, it is exciting and satisfying to see the successful development of a radiopharmaceutical agent which gives the clinical doctor new tools with which to assess function and in vivo biochemistry in nuclear medicine. The clinical application of technetium in nuclear medicine will parallel with the development of technetium chemistry in organic-, analytical-, medical- and biochemistry, and it is likely that useful new Tc-99m radiopharmaceuticals will rapidly make world-wide progress in the future years. The design and synthetic modifications of ligand structure in organic chemistry will impart new biological properties to the technetium complexes. A structure characterization Tc-99m labelled radiopharmaceuticals is highly desirable in analytical chemistry. We take much interest in the structural characterization of Tc-99m complexes stems to establish a structure/in vivo activity relationship in medical chemistry. The current clinical trend is to use Tc-99 radiopharmaceuticals with Tc-99m "carrier-added" experiments for studies of chemical structure and biochemical mechanism of action. Technical difficulties in the various labeling approaches to these bifunctional chelating agents (BCA) which seem promising are often encountered during the ached procedures. High priority is given to development of Tc-99 m radiopharmaceuticals for studies of substrate utilization and localization of specific biological recognition sites. New accomplishments in technetium radiopharmaceutical are likely to be reported in the near future.

Humans↗